Various types of systems have been developed for handling unwanted network data transmission incorporating a number of different technologies. U.S. Pat. No. 6,304,975 issued to Shipley discloses an intelligent network security device (“INSD”) that operates in a local area network (“LAN”) according to an intelligent network security method. The LAN has a plurality of computers and connects to the Internet through a firewall. The INSD resides within the LAN such that data traversing between the LAN and the Internet is accessible thereto. The INSD looks for code and patterns of behavior and assigns a value to perceived attempted security breaches. The INSD then directs the firewall to take any of a prescribed plurality of actions, based upon such value.
U.S. Pat. No. 6,154,775 issued to Coss, et al., describes a system, which provides improved computer network firewalls that include one or more features for increased processing efficiency. A firewall in accordance with the invention can support multiple security policies, multiple users or both, by applying any one of several distinct sets of access rules. The firewall can also be configured to utilize “stateful” packet filtering which involves caching rule processing results for one or more packets, and then utilizing the cached results to bypass rule processing for subsequent similar packets.
To facilitate passage to a user, by a firewall, of a separate later transmission that is properly in response to an original transmission, a dependency mask can be set based on session data items such as source host address, destination host address, and type of service. The mask can be used to query a cache of active sessions being processed by the firewall, such that a rule can be selected based on the number of sessions that satisfy the query. Dynamic rules may be used in addition to pre-loaded access rules in order to simplify rule processing. To unburden the firewall of application proxies, the firewall can be enabled to redirect a network session to a separate server for processing, the only data packets that are transmitted between source and destination network addresses are those that satisfy the blocking policies stored by the blocking data structure. Thus only, “pre-approved” data can flow through such a control mechanism.
U.S. Pat. No. 6,212,633, issued to Levy, et al. discloses a system in which a distributed firewall is utilized in conjunction with a memory-mapped serial communications interface such as that defined by the IEEE 1394 specification to permit secure data transmission between selected nodes over the interface. The distributed firewall incorporates security managers in the selected nodes that are respectively configured to control access to their associated nodes, thereby restricting access to such nodes to only authorized entities. Furthermore, encrypted transmissions may be supported to restrict unauthorized viewing of data transmitted between the selected nodes over the interface. Implementation of the distributed firewall does not modify any critical specifications for the memory-mapped communications interface that would prevent the selected nodes from residing on the same interface as other nodes that adhere to such specifications but that do not support secure data transmission.
U.S. Pat. No. 5,835,726 issued to Shwed, et al. describes a novel system for controlling the inbound and outbound data packet flow in a computer network. By controlling the packet flow in a computer network, private networks can be secured from outside attacks in addition to controlling the flow of packets from within the private network to the outside world. A user generates a rule base that is then converted into a set of filter language instruction. Each rule in the rule base includes a source, destination, service, whether to accept or reject the packet and whether to log the event. The set of filter language instructions are installed and execute on inspection engines that are placed on computers acting as firewalls. The firewalls are positioned in the computer network such that all traffic to and from the network to be protected is forced to pass through the firewall.
Thus, packets are filtered as they flow into and out of the network in accordance with the rules comprising the rule base. The inspection engine acts as a virtual packet-filtering machine that determines on a packet-by-packet basis whether to reject or accept a packet. If a packet is rejected, it is dropped. If it is accepted, the packet may then be modified. Modification may include encryption, decryption, signature generation, and signature verification or address translation. All modifications are performed in accordance with the contents of the rule base. The present invention provides additional security to a computer network by encrypting communications between two firewalls between a client and a firewall. This permits the use of insecure public networks in constructing a WAN that includes both private and public network segments, thus forming a virtual private network.
U.S. Pat. No. 5,968,176 issued to Nessett, et al. discloses a system that provides for establishing security in a network that include nodes having security functions operating in multiple protocol layers. Multiple network devices, such as remote access equipment, routers, switches, repeaters and network cards having security functions are configured to contribute to implementation of distributed firewall functions in the network. By distributing firewall functionality throughout many layers of the network in a variety of network devices, a pervasive firewall is implemented.
The pervasive, multilayer firewall includes a policy definition component that accepts policy data that defines how the firewall should behave. The policy definition component can be a centralized component, or a component that is distributed over the network. The multilayer firewall also includes a collection of network devices that are used to enforce the defined policy. The security functions operating in this collection of network devices across multiple protocol layers are coordinated by the policy definition component so that particular devices enforce that part of the policy pertinent to their part of the network. While other variations exist, the above-described firewall-based designs for handling unwanted network data transmissions are typical of those encountered in the prior art.
The primary objective of the present invention is to eliminate or minimize the liability associated with “packet flooding attacks” initiated from within a local area network linked to an external network. In these attacks, an attacker tries to use up all the bandwidth to the victim by sending data of little or no value (at least to the victim), thereby making more valuable communication with the victim slow or unreliable. The Reverse Firewall invention uses a variety of techniques to determine maximum acceptable rates for data packet transmissions passing through the non-redundant connection between a local area network and an external network provided by the invention. These techniques relate to methods of classifying data packets arriving at the firewall. One such classification involves determining whether packets arriving at the firewall for transmission to the external network are in response to data packets received at the firewall from the external network.
A secondary objective is to maximize the utilization of data packet handling resources within the local area network. This practice involves identifying those data packets that are requests for service, measuring the amount of service requested by each packet, and determining an appropriate amount of resources to be used to provide the requested services. The invention provides facilities for storing and recalling past measurements of the amounts of service provided for each type of service requested. This allows the invention to appropriately allocate the resources available within the local area network.